Pediatric critical cardiovascular and lung disorders are the leading causes of infant mortality in the United States and other developed nations. In addition, there is significant morbidity and mortality in survivors of congenital heart disease surgery and other infants and children with critical heart and lung disorders including those children with primary myocardial diseases, inherited disorders of connective tissue, pulmonary hypertension, chronic lung disease and cerebrovascular injury secondary to many of these diseases. These facts indicate a compelling need for training pediatric physician-investigators oriented towards critical cardiovascular and lung disease. This renewal proposal describes a multidisciplinary training program to prepare clinician-scientists who are in subspecialty training programs for Pediatric Cardiology, Pediatric Critical Care or Neonatology to be rigorously trained for 2 years in either laboratory or clinical investigation related to pediatric critical cardiovascular and lung disease. The program is supported by faculty who are experts in laboratory, clinical and translational research, including expertise in myocardial and vascular biology, lung and pulmonary vascular disorders, genetics, proteomics and biomarkers, computational medicine, imaging, clinical trials and clinical implementation and safety research. The environment provides many opportunities for trainees by virtue of superb centers, core facilities and programs in which faculty participate such as NHLBI supported clinical trials, the Armstrong Institute for Patient Safety and Quality and a Graduate Training Program in Clinical Investigation. Two research tracts are proposed including training for physician scientists (M.D. or M.D., Ph.D.) in A. Laboratory research for physician scientists with an emphasis on translational research. B. Clinical investigation supported by the Graduate Training Program in Clinical Investigation, which may include clinical implementation research which is vitally important in critical care fields. Each of four trainees in the program will have an individual development plan program that is created in consultation with a Steering Committee, a primary mentor and mentorship team. The proposal incorporates strategies to enhance recruitment of underrepresented minority and ethnic groups with leadership from a member of the Pediatric Department diversity committee, and training in the responsible conduct of research. At the conclusion of the program, the trainees will be well prepared to transition towards positions in academic pediatric cardiology and intensive care fields developing funded independent research careers.